Drug Interactions between deutetrabenazine and Phenergan with Dextromethorphan

Using deutetrabenazine together with promethazine can increase the risk of an irregular heart rhythm that may be serious and potentially life-threatening, although it is a relatively rare side effect. You may be more susceptible if you have a heart condition called congenital long QT syndrome, other cardiac diseases, conduction abnormalities, or electrolyte disturbances (for example, magnesium or potassium loss due to severe or prolonged diarrhea or vomiting). In addition, deutetrabenazine can increase the risk and severity of nervous system side effects associated with promethazine, including restlessness, abnormal involuntary muscle movements and Parkinson-like symptoms such as slight shaking, body stiffness, or trouble moving or keeping your balance. Let your doctor know promptly if you experience these problems or other symptoms such as fever, heat intolerance, excessive sweating, stiff muscles, difficulty moving or swallowing, sudden dizziness, lightheadedness, fainting, shortness of breath, or heart palpitations. You should also avoid activities requiring mental alertness such as driving or operating machinery until you know how these medications affect you. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

Using dextromethorphan together with promethazine may increase side effects such as dizziness, drowsiness, confusion, and difficulty concentrating. Some people, especially the elderly, may also experience impairment in thinking, judgment, and motor coordination. You should avoid or limit the use of alcohol while being treated with these medications. Also avoid activities requiring mental alertness such as driving or operating hazardous machinery until you know how the medications affect you. Talk to your doctor if you have any questions or concerns. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

Using dextromethorphan together with deutetrabenazine may increase side effects such as dizziness, drowsiness, confusion, and difficulty concentrating. Some people, especially the elderly, may also experience impairment in thinking, judgment, and motor coordination. You should avoid or limit the use of alcohol while being treated with these medications. Also avoid activities requiring mental alertness such as driving or operating hazardous machinery until you know how the medications affect you. Talk to your doctor if you have any questions or concerns. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.